Preparation of allyl alcohol



Patented July 4, 1933 5 UNITED STATES c -IAn s 0. YounG'AniJ enonsn H. LAW, on enannnsron, vrnoinin, nssrsnons PATENT orri cn To CARBIDE & cAnBon CHEMICALS eoaronarron, A conronnrron on new Year;

1 PREPARATION or ,A LYL nLconon N Drawing.

The invention is a process for making allyl alcohol (CH =CHCH OH) from propylene oxide omonone.

According to the invention the propylene oxide vapor is passed through a reaction chamber filled with a contact catalyst such as activated alumina heated to 200400 C.

The atoms of the propylene oxide molecule are rearranged in two different ways, and in addition to unchanged propylene oxide, the resulting product contains both propionaldehyde and allyl alcohol. The conditions may be regulated so that of the reacted propylene oxide is converted to allyl alcohol. The reaction products are separated by distillation, both the propionaldehyde and allyl 1*? alcohol being recovered.

It has been the general practice to prepare allyl alcohol by means of a reaction between glycerol and oxalic acid. This process does not produce allyl alcohol in satisfactory 1'2 yields, and the process is difficult to operate,

hence the advantages of this invention will be apparent.

It is well known that propylene oxide when passed over a contact catalyst such as j .3 alumina, heated to about 250 0., produces considerable quantities of propionaldehyde, but the formation of allyl alcohol in the process has not been reported. We have discovered that by careful regulation of tempera- .3 tures and rates of flow through the zone of t are not allowed to stand in contact with the catalyst, but are in continuous motion thereover at a high rate of speed) through the catalyst chamber heated to 275 C. The exit gases are condensed and distilled. Approxi- 5 mately 50% of the propylene oxide is recov- Application filed. December 12, 1930. Serial NaEOsZfiOQ.

ered unchanged. The balance is fractionated, and propionaldehyde, representing about of the reacted propylene oxide, is removed. Water is added to the remainder,

and a constant boiling mixture of allyl alcohol and water, containing allyl alcohol is obtained.

The reaction as described is quite exothermic, and in order to control the temperature,

it is desirable to pass some inert gas or vapor through the reaction tube admixed with the propylene oxide vapor. For this purpose nitrogen, Water vapor, etc., may be employed. If the temperature is allowed to rise substantially beyond the specified limits, i. e. 200" 400 6., or if the propylene oxide vapor is permitted to remain too long in the reaction tube, further changes and decompositions may occur, resulting in the loss of valuable material.

It is preferred to use activated alumina as the catalyst, but other catalysts such as finely divided metals and oxides may be used. Thus, thoria, titania, etc., may be substituted for the activated alumina in the reaction chamber. We prefer to prepare the activated alumina by precipitating aluminum hydroxide from a hot concentrated solution of aluminum nltrate with sodium hydroxide; the

aluminum hydroxide is filtered, dried, and; made into pellets which are then washed for several hours in a stream of hot Water and ignited. A very active porous catalyst is produced. A satisfactory catalyst may also be made by preparing aluminum ethoxide, by the reaction of ethyl alcohol with aluminum,

evaporating to dryness, steaming and igniting.

The eificlencies and rates of production of allyl alcohol may vary considerably with the titania and thoria at a temperature between about 200 and about 400 C.

2. The process of making allyl alcohol which comprises rapidly and continuously 5 passing propylene oxide vapor over a contact catalyst of the group consisting of alumina, titania and thoria at a temperature of about 200 to about 400 C., said propylene oxide va 301' being admixed with an inert diluent where y temperature control and prevention of long contact of the propylene oxide vapor with said catalyst is efiected.

8. The process of making allyl alcohol tures.

CHARLES O. YOUNG. GEORGE H. LAW. 

